Fixing apparatus and image forming apparatus including the same
a technology of fixing rollers and fixing rollers, applied in the direction of electrographic process equipment, instruments, optics, etc., can solve the problems of temperature sensors and the fixing rollers rubbing against each other, degradation of fixing quality, damage to the surface of the fixing roller, etc., and achieve the effect of preventing the occurrence of fixing failur
Inactive Publication Date: 2009-08-04
SHARP KK
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- Application Information
AI Technical Summary
Benefits of technology
This solution prevents fixing failures by ensuring consistent surface temperatures across the fixing roller, maintaining high-quality prints even with large-size paper sheets by adjusting the control temperature according to the number of processed sheets, thus avoiding unnecessary heat supply and maintaining optimal fixing conditions.
Problems solved by technology
However, an arrangement in which a plurality of temperature sensors are disposed so as to be in contact with the fixing roller causes the temperature sensors and the fixing roller to rub against each other.
This may cause damage to the surface of the fixing roller, thus resulting in degradation in fixing quality.
Especially, an arrangement in which the temperature sensors are disposed so as to press-contact the fixing roller tends to be a factor responsible for damage to the surface of the fixing roller.
However, when temperatures of the fixing roller are controlled by using the center section temperature sensor and the end section temperature sensor disposed in the above manner, fixing failure can occur in continuous printing depending upon a paper size used.
This problem is caused by control of energization of the sub-heater on the basis of a result of detection carried out by the end section temperature sensor.
However, it is difficult to perform control so that a temperature of the sheet passing region becomes a preset fixing temperature by the temperature sensor which is disposed outside the maximum-size sheet passing region.
Since the heater is turned on when the surface temperature of the passing region become lower than the preset fixing temperature, there is loss of time of thermal propagation inside the fixing roller.
This event occurs due to unnecessary heat supply by the main heater.
When the main heater keeps being turned on, such an unnecessary heat supply by the main heater causes unnecessary heat supply to the end section of the fixing roller.
Due to such variations in temperature on the surface of the fixing roller, a paper sheet suffers from fixing failure such that the paper sheet has a lower gloss at a part that have passed through the center section of the fixing roller where a temperature is high than at parts that have passed through the end sections of the fixing roller where a temperature is low.
Method used
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[0045]An image forming apparatus according to an embodiment of the present invention is explained below with reference to FIGS. 1 through 8.
[0046]FIG. 2 is a longitudinal sectional view of an image forming apparatus 1 of the present embodiment. The image forming apparatus 1 of the present embodiment forms a single color image with respect to a predetermined sheet (recording sheet) in accordance with image data transmitted externally and / or image data read by the image forming apparatus 1 itself. The image forming apparatus 1, as illustrated in FIG. 2, includes an exposure unit 2, a developing unit 3, a photoreceptor drum 10, a transfer unit 11, an electrostatic charging unit 4, a cleaning device 5, a fixing unit (fixing apparatus) 6, a paper feed tray 8, a output paper tray 9, and a control section 50.
[0047]The electrostatic charging unit 4 is a section for electrostatically charging a surface of the photoreceptor drum 10 to a predetermined potential evenly. The electrostatic chargi...
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In a fixing apparatus of the present invention, an end section fixing control temperature changing section selects an end section fixing control temperature in accordance with the number of paper sheets that have been processed in one continuous printing process. A sub-heater on / off determining section turns on or off a sub-heater in accordance with a temperature detected by an end section temperature sensor and the end section fixing control temperature selected by the end section fixing control temperature changing section. This prevents the occurrence of fixing failure even in continuous printing with respect to large-size paper sheets in an arrangement in which a temperature sensor is disposed outside a maximum-size sheet passing region at an end section of a fixing roller and controls energization of a heater which is disposed corresponding to the end section of the fixing roller in accordance with a temperature detected by the temperature sensor.
Description
[0001]This Nonprovisional application claims priority under 35 U.S.C. ยง 119(a) on Patent Application No. 73378 / 2006 filed in Japan on Mar. 16, 2006, the entire contents of which are hereby incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates to (i) a fixing apparatus incorporated into an image forming apparatus using an electrophotographic process, for example, a copying machine, a facsimile, a printer, and a multifunction machine, and (ii) an image forming apparatus using the same.BACKGROUND OF THE INVENTION[0003]Conventionally, a heat roller fixing method has been generally used in a fixing apparatus incorporated into an image forming apparatus using an electrophotographic process. A copying machine and a printer are examples of such image forming apparatus. In the heat roller fixing method, a paper sheet (recording material) holding an unfixed toner image thereon passes between a heated fixing roller and a pressure roller which is press-contacted to...
Claims
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IPC IPC(8): G03G15/20
CPCG03G15/2039
InventorMIKITA, TOSHIYAIDE, ATSUSHIAOKI, KOHJITAKAI, YASUHIRO
OwnerSHARP KK